Re-evaluation of the $^{22}$Ne($,$)$^{26}$Mg and $^{22}$Ne($,n$)$^{25}$Mg reaction rates Institutional Repository Document uri icon


  • The competing $^{22}$Ne($alpha,gamma$)$^{26}$Mg and $^{22}$Ne($alpha,n$)$^{25}$Mg reactions control the production of neutrons for the weak $s$-process in massive and AGB stars. In both systems, the ratio between the corresponding reaction rates strongly impacts the total neutron budget and strongly influences the final nucleosynthesis. The $^{22}$Ne($alpha,gamma$)$^{26}$Mg and $^{22}$Ne($alpha,n$)$^{25}$Mg reaction rates was re-evaluated by using newly available information on $^{26}$Mg given by various recent experimental studies. Evaluations of The evaluated $^{22}$Ne($alpha,gamma$)$^{26}$Mg reaction rate remains substantially similar to that of Longland {it et al.} but, including recent results from Texas A&M, the $^{22}$Ne($alpha,n$)$^{25}$Mg reaction rate is lower at a range of astrophysically important temperatures. Stellar models computed with NEWTON and MESA predict decreased production of the weak branch $s$-process due to the decreased efficiency of $^{22}$Ne as a neutron source. Using the new reaction rates in the MESA model results in $^{96}$Zr/$^{94}$Zr and $^{135}$Ba/$^{136}$Ba ratios in much better agreement with the measured ratios from presolar SiC grains.

author list (cited authors)

  • Adsley, P., Battino, U., Best, A., Caciolli, A., Guglielmetti, A., Imbriani, G., ... Hirschi, R.

complete list of authors

  • Adsley, Philip||Battino, Umberto||Best, Andreas||Caciolli, Antonio||Guglielmetti, Alessandra||Imbriani, Gianluca||Jayatissa, Heshani||Cognata, Marco La||Lamia, Livio||Masha, Eliana||Massimi, Cristian||Palmerini, Sara||Tattersall, Ashley||Hirschi, Raphael

publication date

  • May 2020